Effect of medium composition and light supply on in vitro shoot proliferation in Ilex paraguariensis (Aquifoloaceae)

Abstract

In vitro regeneration of shoots from nodal segments (containing one axillary bud) of 'yerba mate' (Ilex paraguariensis St. Hil.) was studied under defined nutritional and environmental conditions. Shoot regeneration occurred in several media tested. The best nutrient medium contained the mineral salts and vitamins of Murashige and Skoog medium at 1/4 strength, plus 3% sucrose and 1 mg 6-benzyladenine L-1. The explants were incubated at 27°C, 14 hr photoperiod (116 μmol m-2s-1). As much as 60% of the nodal segments cultured formed multiple shoots (with an average of 2.8 shoots per explant). Pretreatment of the donor plants with darkness as well as the culture under different light treatments did not modified these results. Rooting of regenerated shoots was poor and the plantlets regenerated did not survived when transferred to soil The use of this protocol for micropropagation of selected clones of Ilex paraguariensis is discussed.